Polish Populations Research Articles

Population genetics of the endangered obligatorily myrmecophilous butterfly Phengaris (=Maculinea) arion in two areas of its European range

Abstract The socially parasitic Phengaris arion is one of the most threatened butterfly species in Europe. Using 12 microsatellite loci, we studied the genetic structure of 14 ecologically diverse populations (285 individuals) originating from two distinct areas of the European distribution range (Poland and Italy). Italian populations were more differentiated (FST = 0.124) than Polish populations (0.073). Nevertheless, in contrast to the results of previous studies on mitochondrial (COI) and nuclear (EF‐1α) genes, indices of genetic variability were higher in Poland. Within‐population genetic variability in Italy decreased southwards, whereas in Poland no similar gradient of changes was detected. Bayesian clustering of individuals (STRUCTURE, BAPS) and analysis of principal components (PCA) indicated a genetic structure in Italian sampling sites that was more pronounced than in Poland. The analysis also suggested a common evolutionary history for populations inhabiting the northern slopes of the Alps and Central Europe, or that the alpine populations are localised in a mixed zone of different post‐glacial colonisation routes (STRUCTURE, PCA). In addition, implementation of spatial information into the analysis (BAPS) suggested that the observed pattern of differentiation could be shaped simply by landforms as all Italian sampling sites and two mountainous Polish sites formed separate cluster. The pattern of ecological variation did not influence genetic structure and no grounds for separation of subspecies (P. arion ligurica and P. arion obscura) were found. Our results are therefore in agreement with conclusions inferred from other studies carried out in Europe on P. arion.

Genetic diversity in Hucul and Polish primitive horse breeds

Abstract. Pedigree and molecular data were used to evaluate genetic diversity in the Polish populations of the Polish primitive horse (also known as Polish Konik) and Hucul breeds over the time period of 30 years (1980–2011). Based on genotypes in 12 microsatellite loci (for 3865 Polish primitive horses and 1627 Huculs), as well as on pedigree data derived from over 7000 individuals (both breeds), several indices describing structure of the analysed populations were estimated. For both analysed breeds, we observed an increasing trend of inbreeding since 1980 which seems to be much more stable (oscillating around 10 % in the Polish primitive horse and 5 % in Hucul) since the beginning of 2000s when they were included in conservation programs in Poland. We observed that generally, indices related to genetic diversity are higher in the Hucul breed. Our study indicated that genetic diversity in the Polish primitive horse and Hucul breeds in Poland is still relatively high and conservation programs should be continued to keep it on the "safe" level in the future.

Genes of the extinct Caucasian bison still roam the Białowieża Forest and are the source of genetic discrepances between Polish and Belarusian populations of the European bison,Bison bonasus

European bison (Bison bonasus) populations from both the Polish (PL) and the Belarusian (BY) sides of the Bialowieza Forest represent the Lowland genetic line (LB line) – progeny of the Lowland bison (Bison bonasus bonasus) that inhabited western, central, and south-eastern Europe in historical times. During the species recovery, one of the founders was a descendant of the extinct Caucasian bison (Bison bonasus caucasicus) and its descendants formed the other genetic line – Lowland–Caucasian (LC). There have been justified suspicions that LB European bison in the former Soviet Union had undergone cross-mating with the LC line. We performed a comparative genetic analyses on European bison from the BY and PL parts of the Bialowieza Forest, the LC line and extinct Caucasian bison, based on a set of 19 microsatellite markers and 1512 bovine single nucleotide polymorphism (SNP) markers, polymorphic in at least one of the studied populations. Although genetic variability (mean allele number and expected heterozygosity) for both populations were similar, the FST jack-knifing and principal component analyses PCA revealed highly significant differences between PL and BY bison from the Bialowieza Forest. Examining DNA of the extinct Caucasian bison revealed that at least part of the genetic variants found in the BY, but not the PL, population were of Caucasian origin. The results indicate that the contemporary population of European bison from the BY part of the Bialowieza Forest should not be regarded as a LB line. The results also suggest that the actual global population size of the LB line European bison is only a half of its official status. Consideration of the presented results are crucial in determining management actions and policy decisions in order to conserve LB line bison within the Bialowieza Forest – its natural refuge. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 752–763.

Beta-Glucocerebrosidase Gene Mutations P.Asn409Ser and P.Leu483Pro in Polish Patients with Parkinson's Disease

Background: The aim of his study was to evaluate the frequency of two most frequent GBA gene mutations in heterozygote state in patients with early and later onset Parkinson's disease in Polish populations. Methods and findings: Patients with Parkinson's disease; 115 non-demented with early onset disease (<45 year-old) and 155 patients with onset over 45 year-old were recruited to the study. The p.Asn409Ser and p.Leu483Pro screening was performed with the PCR-RFLP and direct sequencing methods. In the group of 270 PD patients, 11 heterozygotes for mutations in the GBA gene were identified (carrier frequency 4.07%). Among patients with early onset disease carrier frequency was 4.34% compared to 3,87% in the group of later onset. Conclusion: The study yielded that carrier frequency of GBA mutation in polish population was comparable to other European populations p.Asn409Ser mutation dominates in patients with early onset PD disease

Role of the X-linked gene GPR174 in autoimmune Addison's disease.

Autoimmune endocrinopathies demonstrate a profound gender bias, but the reasons for this remain obscure. The 1000 genes on the X chromosome are likely to be implicated in this inherent susceptibility; various theories, including skewed X chromosome inactivation and fetal microchimerism, have been proposed. GPR174 is an Xq21 putative purinergic receptor that is widely expressed in lymphoid tissues. A single-nucleotide polymorphism, rs3827440, encoding Ser162Pro, has recently been associated with Graves' disease in Chinese and Polish populations, suggesting a role of this X chromosome gene in autoimmune disease. We investigated the role of rs3827440 in a UK cohort of patients with autoimmune Addison's disease (AAD). Samples from 286 AAD cases and 288 healthy controls were genotyped using TaqMan single-nucleotide polymorphism genotyping assays (C_25954273_10) on the Applied Biosystems 7900HT Fast real-time PCR system. Using a dominant (present/absent) model, the serine-encoding T allele of rs3827440 was present in 189 of 286 AAD patients (66%) compared with 132 of 288 unaffected controls (46%) [P = .010, odds ratio 1.80 (5%-95% confidence interval 1.22-2.67)]. An allele dosage model found a significant excess of the T allele in AAD patients compared with controls [P = .03, odds ratio 1.34 (5%-95% confidence interval 1.07-1.67)]. We have demonstrated a significant association of this X chromosome-encoded immunoreceptor with AAD for the first time. This X-linked gene could have a more generalized role in autoimmunity pathogenesis: G protein-coupled receptors are promising drugable targets, and further work to elucidate the functional role of GPR174 is now warranted.

Persistent Müllerian duct syndrome (PMDS) in the Polish free-ranged bull populations of the European bison (Bison bonasus L.)

This study describes the diversity of vestigial male uteri of the European bison (Eb) examined for: (1) morphology, (2) glycoprotein localization, (3) total protein and glycoprotein profiles, (4) steroid concentrations, and (5) PMDS based on the mutation of AMH and AMHR2 genes. Uteri of adult bulls (5–12 years old) were compared to a uterus of a juvenile female (6 months old). Male uterine proteins were analyzed in parallel to secretory endometrial proteins of pseudo-pregnant pig (PsEND) and BSA used as profile-controls. Hematoxylin/eosin-staining revealed the diversity of male uterine morphology, including lumen size/shape, endometrial (END) gland density, luminal knob-like epithelial structures and multiple intrauterine cells proliferating within the lumen. PAS-staining revealed the presence of glycoproteins restricted to luminal epithelial cells and END glands. Heterologous total protein PAGE-profiles (20–66kDa) revealed two dominant fractions (66 and 45kDa), similar to PAS-profiles (67 and 47kDa) in male and female uterine tissues. In male uterine tissues, androstendione and progesterone, but not testosterone, estrone or estradiol concentrations were lower than in the female. Sequencing of AMH- and AMHR2-like amplicons allowed identification of these gene mutations in Eb. Our results provide novel data regarding PMDS, demonstrating the diversity of uterine morphology, glycoprotein mass/profile, steroid concentration and AMH/AMHR2 mutations in Eb bulls.

The prevalence and genetic characterization of Chlamydia psittaci from domestic and feral pigeons in Poland and the correlation between infection rate and incidence of pigeon circovirus

Chlamydiosis is a zoonotic disease caused by Chlamydia psittaci that occurs in a wide range of bird species. High infection rates with C. psittaci are found in pigeons, which can act as vectors transmitting this bacterium to poultry and humans. Chlamydia shedding by pigeons is intermittent and can be activated by stressors or immunosuppression. The most common immunosuppressive factor for pigeons is a pigeon circovirus (PiCV) infection. The main aim of the study was to evaluate the prevalence of C. psittaci in Polish populations of domestic and feral pigeons (Columba livia) in the context of its correlation with PiCV infections. The second objective was to determine the genetic characteristics of Polish C. psittaci isolates. The study was conducted on 377 pigeon samples (276 domestic and 101 feral pigeons) collected from pigeons from different regions of Poland. The average prevalence of C. psittaci in the Polish pigeon population was determined at 6.8%, and it was higher in domestic than in feral pigeons. This is the first ever study to suggest a potential correlation between C. psittaci and PiCV infections, which could be attributed to the fact that there are 2 to 3 times more pigeons infected with C. psittaci and coinfected with PiCV than pigeons infected with C. psittaci alone. This trend was observed mainly in the population of sick pigeons. As many as 88.2% of isolates were recognized as belonging to genotype B, and the remaining isolates were identified as belonging to genotype E. The isolates analyzed in this study demonstrated low levels of genetic variation (96–100% homology among the isolates and in relation to reference strains). Chlamydia psittaci could be expected to spread across pigeon populations due to the high probability of mutual infections between birds and the increasing number of PiCV infections.

A physiologically based model for spirometric reference equations in adults.

A spirometric reference equation consists of a mathematical model with constants and coefficients optimized to fit a specific data set from healthy individuals. Commonly applied models are selected on statistical rather than physiological considerations. A predetermined model with constants and coefficients optimized to various populations would enable interpretable and interesting comparisons between populations. Lubiński and Gólczewski recently presented a piecewise linear model with constants and coefficients claimed to be physiologically interpretable (Lubiński model). Three questions were addressed: Is the Lubiński model as useful clinically as other models: multiple linear, piecewise polynomial and exponential with splines? Will reference equations based on the Lubiński model and optimized to a Swedish and to a Polish population allow for interpretable comparisons? Are three well-known reference equations clinically useful in the Swedish adult population? A recent Swedish random population sample with high-quality spirometric measurements enabled the present analyses. When optimized to fit the Swedish population sample, the Lubiński model and two other models provided accurate predictive normal values. Interesting differences were demonstrated between the Polish and Swedish populations. The proportion of subjects below lower limit normal was adequate for the piecewise polynomial equations but too low and not clinically useful for the advocated exponential equations with splines. It is concluded that the Lubiński model is clinically as useful as other models, and it adds important value and is recommended for future spirometric reference equations for adults. The advocated exponential equations with splines are not recommended for Swedish adults because of too wide normal limits.

A study of the genetic variation of the aquatic fern Marsilea quadrifolia L. preserved in botanical collections in Poland and originated from natural populations in Europe

Aim of the present study was to evaluate the genetic diversity of selected European populations of Marsilea quadrifolia L. and to assess the applicability of those genetic resources of Marsilea quadrifolia L. that have been preserved in Polish botanical gardens, for the reintroduction of this species into its historical range in Poland. Three Polish populations that originated from botanical collections (Zabrze, Żarów and Puławy) and four natural populations (two from Slovakia (Slovakia I and Slovakia II), one from France and one from Germany) were analyzed using Amplified Fragment Length Polymorphism (AFLP) markers. A very low level of genetic variation was found both within and between the populations in the study, which likely resulted from a genetic bottleneck probably caused by human activities. Plants with the same AFLP fingerprint were found across several populations; however, singleton samples with a unique AFLP band pattern were also present within all of the populations. The presence of singletons led to relatively high values of Simpson's diversity index, which may suggest a considerable effect of mutations and some possibility of sexual reproduction as sources of the observed variation. The partitioning of molecular variance was calculated using hierarchical AMOVA, which showed that a negligible value of only 0.81% of the variation was explained by the category of population, i.e. plants originating from the botanical collections or from the natural habitats. This result indicates that M. quadrifolia populations from botanical collections resemble natural populations in terms of the level of their genetic variation and that the populations that were obtained from the Polish collections could be used for the successful reintroduction of this species into its historical range in Poland, and a similar situation may be given also in other areas of occurrence of this plant that is under threat throughout its area of occurrence in Europe.

Accumulation of biomass and phenolic compounds in Polish and Mongolian great burnet (Sanguisorba officinalis L.) populations

Summary Eight Polish and six Mongolian great burnet populations were evaluated ex situ in respect of the mass of underground organs and accumulation of biologically active compounds. In the raw materials collected in autumn of the second year of plant vegetation, total content of tannins and phenolic acids as well as the content of phenolic compounds identified by HPLC were determined. Distinct differences between Polish and Mongolian populations and their high intraspecific variability, concerning analysed parameters, was observed. The mass of underground organs of Polish populations was higher than in Mongolian ones (595.0 and 523.5 g × plant-1, respectively, for fresh mass). Polish populations were characterised by significantly higher total content of tannins and phenolic acids (6.02 and 1.60%, respectively) in comparison with Mongolian ones (2.89 and 0.97%, respectively). In the investigated raw materials eight phenolic compounds were identified, namely: /-/-epigallocatechin, /+/-catechin, /-/-epicatechin, /-/-epicatechin gallate, /-/-epigallocatechin gallate, astragalin, ellagic and gallic acids. In all populations, the dominating compound, was /-/-epigallocatechin. The contents of /-/-epigallocatechin, /-/-epicatechin gallate and gallic acid were distinctly higher in Polish populations.

Morphological and genetic characteristics of the anisakid nematode Raphidascaris acus from the southwest Caspian Sea: evidence for the existence of sibling species within a species complex.

Recently, it has been shown that many nematode species are in fact species complex, using exact morphological and genetic studies. In this case, there are no such studies related to the genus Raphidascaris Railliet & Henry, 1915. Herein, the morphological and genetic variations among the Iranian population of the species Raphidascaris acus (Bloch, 1779) Railliet & Henry, 1915 and the other allopatric populations with morphological and genetic information were compared to show whether this species can be considered as a species complex. R. acus is an anisakid species and has been frequently reported from different host species from the Caspian Sea. Nonetheless, there are no morphological and genetic information for this species from the region. In the present study, a total of 20 specimens of R. acus were collected from Esox lucius Linnaeus, and the morphology of the Caspian population of this species was surveyed for the first time using both light and scanning electron microscopy. Meanwhile, some parts of ribosomal DNA (rDNA) including internal transcribed spacer 1 (ITS1), 5.8 s, and ITS2 were sequenced and presented as the genetic marker for this species. To understand whether R. acus can be considered as a species complex, the Caspian population of this species was compared morphologically with the allopatric populations of Czech and Canada and genetically with the allopatric population of Poland (Vistula lagoon). Morphologically, there was no difference between the Caspian and Czech populations, but the Caspian and Canadian populations differed in the length of ejaculatory duct and the presence of small triangular elevation between the bases of subventral lips. The nucleotide difference between the Caspian and Polish populations was 4.48%. In comparison with the interspecific genetic distances in the genus Raphidascaris, this value is notable. In conclusion, based on morphological and genetic differences among the allopatric populations of R. acus, this species is probably a species complex. Nonetheless, the definitive taxonomic decision in recognizing R. acus as a species complex and the description of its sibling species depend on surveying other allopatric populations morphologically and genetically accompanied by an evaluation of reproductive isolation among them.

Population genetic data and forensic parameters of 30 autosomal InDel markers in Santa Catarina State population, Southern Brazil.

The application of DNA technology in forensic investigations has grown rapidly in the last 25 years and with an exponential increase of short tandem repeats (STRs) data, usually presented as allele frequencies, that may be later used as databases for forensic and population genetics purposes. Thereby, classes of molecular markers such as single nucleotide polymorphisms and insertions/deletions (InDels) have been presented as another option of genetic marker sets. These markers can be used in paternity cases, when mutations in STR polymorphisms are present, as well as in highly degraded DNA analysis. In the present study, the allele frequencies and heterozygosity (H) of a 30 InDel markers set were determined and the forensic efficacy was evaluated through estimation of discrimination power (DP), match probability, typical paternity index and power of paternity exclusion in 108 unrelated volunteers from the State of Santa Catarina (South Brazil). The observed H per locus showed a range between 0.370 and 0.574 (mean = 0.479). HLD128 was the locus with the highest DP (DP = 0.656). DP for all markers combined was greater than 99.9999999999646 % which provides satisfactory levels of information for forensic demands. Genetic comparisons (exact tests of population differentiation and pairwise genetic distances) revealed that the population of Santa Catarina State differs from Korea and USA Afro-American populations but is similar to the Portuguese, German, Polish, Spanish and Basque populations.

High Stability of a Mitochondrial Genetic Marker mtCOII in Polish Colorado Potato Beetle Populations

Colorado potato beetle (CPB) (Leptinotarsa decemlineata (Say in Journal of the Academy of Natural Sciences of Philadelphia 3: 298–331, 1824)) (Coleoptera: Chrysomelidae) is one of the most serious potato pests. It has been reported worldwide, from North America to Europe and Asia. In this study we analyzed the genetic diversity of a mitochondrial DNA marker – a second subunit of cytochrome oxidase (mtCOII) in Polish CPB populations to assess the possible changes of this gene sequence over time and over the country, influencing the intra-specific variability of CPB. During a three-year survey in Polish potato fields the beetles were collected from 20 evenly spaced locations of varying climatic and geographic conditions, and the nucleotide sequence of this marker was analyzed. Our research revealed that in spite of three years of sampling the mitochondrial haplotype in all individuals was fixed, and no single nucleotide change was found in any individual, indicating a high stability of this maternally inherited marker in L. decemlineata. This finding about the level of biodiversity is of importance for plant protection strategies.

Analysis of studies of the effectiveness of a biological method of protection for organic crops

SUMMARY As a result of intensive changes in plant production and of environmental changes in agrocenoses, certain agrophages, such as slugs, have in recent years been causing ever increasing amounts of damage to crops of agricultural, horticultural and orchard plants. As a result of the European Parliament and Council Directive adopted on 13 January 2009, the countries of Europe have been required to implement integrated plant protection. One of the principles of this protection is the implementation of strategies which minimize the use of chemical pesticides. Moreover, in accordance with decisions of the European Commission, many active substances have been or are to be withdrawn from the list of available pesticides. An example is metaldehyde, which is to be withdrawn from use in EU countries in the next few years (Commission Decision C/2008/7637 of 5 December 2008). It therefore becomes necessary to seek environmentally safe substances and to develop non-chemical methods for protecting plants against harmful slugs. An alternative to chemical molluscicides is the parasitic nematode Phasmarhabditis hermaphrodita. Studies have been made of the effectiveness of this biological method in combating Polish populations of the invasive slug species Arion lusitanicus. This was an incomplete multivariate study, i.e. not all variables could be observed for all treatments on all experimental units. Multivariate model of observations has been derived and a method of analysis has been described. The results of these studies provide a basis for the development of environmentally friendly methods of protecting plants against harmful slugs.

An Updated Analysis with 85,939 Samples Confirms the Association Between CR1 rs6656401 Polymorphism and Alzheimer's Disease.

The complement receptor 1 (CR1) rs6656401 polymorphism was first identified to be associated with Alzheimer's disease (AD) in European ancestry. However, the following studies reported weak or no significant association in Chinese, Japanese, Korean, African-American, Polish, and Canadian populations. We think that these negative results may have been caused by either relatively small sample sizes compared with those used for the previous genome-wide association studies (GWAS) in European ancestry or the genetic heterogeneity of the rs6656401 polymorphism in different populations. Here, we reevaluated this association using the relatively large-scale samples from previous 24 studies (N = 85,939, 30,100 cases and 55,839 controls) by searching the PubMed, AlzGene, and Google Scholar databases. Using additive model, we did not identify significant heterogeneity among the 24 studies. We observed significant association between the rs6656401 polymorphism and AD in pooled populations (P = 1.82E-26, odds ratio (OR) = 1.18, 95% confidence interval (CI) 1.15-1.22). In subgroup analysis, we identified significant results in East Asian population with P = 5.00E-04, OR = 1.31, 95% CI 1.13-1.52. To our knowledge, this is the first meta-analysis to investigate the association between rs6656401 polymorphism and AD in East Asian, African-American, Canadian, and European populations. Our analysis further supports previous findings that the CR1 rs6656401 polymorphism contributes to AD susceptibility. We believe that our findings will be very useful for future genetic studies on AD.

Total and methylmercury in soft tissues of white-tailed eagle (Haliaeetus albicilla) and Osprey (Pandion haliaetus) collected in Poland.

Mercury (Hg) contamination in piscivorous birds, especially methylmercury (MeHg), has been drawing much attention worldwide in regard to its bioaccumulation and biomagnification in food chains. In this study on Hg in the soft tissues of white-tailed eagles (n = 22) and ospreys (n = 2) from Poland, total Hg (THg) range was 0.15–47.6 while MeHg range was 0.11–8.05 mg kg−1 dry weight. In both species, median THg and MeHg concentrations were lower in the muscle and brain than in the liver and kidney. Median nephric residues were just under 3 and 5 mgTHg kg−1 or 0.9 and 3.7 mgMeHg kg−1 for white-tailed eagle and osprey, respectively. In Norwegian data from the 1970s and in our results, MeHg in the muscle of white-tailed eagle was ~60 % THg (%MeHg = MeHg/THg × 100), lower than in other piscivorous birds. A clear similarity in THg tissue levels was found between Polish and German populations of white-tailed eagles.

Chinese pond mussel Sinanodonta woodiana (Lea, 1834) (Bivalvia): origin of the Polish population and GenBank data

D DNA sequences of the mitochondrial cox1 gene were analysed in 4 new local populations of Sinanodonta woodiana (Bivalvia) in Poland, in the first reported Polish population, and in a population from Hungary. The gene sequences of Polish specimens were identical to those of specimens from Hungary, Italy and Ukraine, but different from those of Romanian specimens (data from GenBank). According to fish farm documentation, S. woodiana had spread in Poland by 2 routes: i) direct import of fish infected by glochidia of S. woodiana from Hungary; and ii) indirectly, by the major distributor of thermophilous fish in Poland, Goslawice Fish Farm, which started to import Hungarian fish in the 1960s. The genetic analysis and available documentation unambiguously confirm that Polish populations of S. woodiana derive from a source population in Hungary. In addition, we noticed doubtful identification of this species in GenBank data and further research is needed to resolve this problem.

High genetic similarity between Polish and North European Scots pine (Pinus sylvestris L.) populations at nuclear gene loci

Nucleotide polymorphisms in a set of 32 nuclear genes were studied in 19 mountain, peatbog and lowland populations of Scots pine representing known phenotypic races and populations of presumably relict character for the species in Poland. At 29 genes, the pattern of genetic variation was compared to 11 reference populations from Northern, Western and Southern Europe. Similar levels of nucleotide polymorphism and excess of low-frequency mutations were observed in Polish populations (π tot = 0.0055, D = −0.308) and as compared to the reference samples (π tot = 0.0054, D = −0.170). Bayesian assignment and conventional frequency-based statistics indicate that Polish populations share the same genetic background at the analysed nuclear gene markers. However, the populations showed a much closer genetic relationship with North European samples than other regional groups of populations. Across the very uniform genetic background of the populations, we identified several genes with outlier patterns of haplotype, polymorphism frequency variation and departures from compound neutrality tests. Our data indicate that the Central and North European parts of the Scots pine distribution seem particularly suitable for association genetic studies to link phenotypic and genetic variation at a large geographical scale.

Covariation between mean vole density and variability drives the numerical response of storks to vole prey

AbstractHušek et al. (Popul Ecol 55:363–375, 2013) showed that the numerical response of storks to vole prey was stronger in regions where variability in vole density was higher. This finding is, at first sight, in contradiction with the predictions of life‐history theory in stochastic environments. Since the stork productivity‐vole density relationship is concave, theory predicts a negative association between the temporal variability in vole density and stork productivity. Here, we illustrate this negative effect of vole variability on stork productivity with a simple mathematical model relating expected stork productivity to vole dynamics. When comparing model simulations to the observed mean density and variability of thirteen Czech and Polish vole populations, we find that the observed positive effect of vole variability on stork numerical response is most likely due to an unusual positive correlation between mean and variability of vole density.

Body mass index in young school-age children in relation to organochlorine compounds in early life: a prospective study

To investigate the association between maternal pregnancy and estimated postnatal serum concentrations of the organochlorines 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) and body mass index (BMI) z-scores in 5- to 9-year-old children. Maternal sera from the INUENDO birth cohort (2002-2004) comprising mother-child pairs (N=1109) from Greenland, Warsaw (Poland), and Kharkiv (Ukraine) were analysed for CB-153 and p,p'-DDE, using gas chromatography-mass-spectrometry, and were grouped into tertiles for statistical analyses. A toxicokinetic model was used to estimate the first 12 months cumulative exposure to the compounds. Associations between these compounds and child age- and sex-specific BMI z-scores were calculated at follow-up (2010-2012), using multiple linear regression analysis. No clear associations between pregnancy CB-153 and p,p'-DDE and child BMI were observed (the pooled differences in BMI z-score (95% confidence interval) comparing 3rd tertile to 1st tertile were -0.07 (-0.32 to 0.18) and -0.10 (-0.30 to 0.10) kg m(-2), respectively). For postnatal CB-153 and p,p'-DDE and BMI, the overall differences in BMI z-score comparing 3rd tertile to 1st tertile were 0.12 (-0.15 to 0.39) and -0.03 (-0.20 to 0.27) kg m(-2), respectively. This follow-up study of Greenlandic, Polish and Ukrainian populations showed no clear association between pregnancy and postnatal exposure to p,p'-DDE and CB-153 and BMI at the age of 5-9 years.